This invention relates to an indicator in a package which will show whether or not the original seal on the package has been broken and contents exposed to air. In particular it relates to packages of food, pharmaceuticals, chemical materials, clinicals and similar materials to detect and demonstrate whether there has been any tampering. Various methods for ascertaining the integrity of a package have been previously described using certain chemical and physical tests to indicate a change in the environment within the package. Thus, a change in moisture content, exposure to light, loss of packaging gas and color changes resulting from the presence of oxygen have all been suggested. Representative prior art includes U.S. Pat. Nos. 1,910,952; 1,055,595; 1,095,313; 3,899,295; 4,098,577; 3,463,532; 4,169,811; and 4,349,509.
However, the prior art devices and methods suffer from one or more disadvantages as, for example, high cost, lack of reliability, and insufficient protection against deliberate tampering.
One object of the present invention is to provide within a sealed package an indicator which will show in a reliable way whether or not the package has been opened.
A further object of this invention is to provide such an indicator having greater resistance to tampering than prior art devices and methods.
Other objects and advantages of this invention will be apparent from the description and claims which follow, taken together with the appended drawing.